1. Field of the Invention
This invention relates to a paint booth with a purifier for removing paint mist contained in air in a spray chamber.
2. Description of the Related Art
A paint booth is used for painting operation by means of a paint sprayer such as a spray nozzle in a spray chamber. The paint booth is used to prevent a working environment in the spray chamber from getting worse or prevent paint mist from being discharged to the outside.
A paint booth of the Venturi booth type is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-273292 (Patent Document 1). In the paint booth of the Venturi booth type, air containing paint mist is drawn into an eddy chamber by an exhaust fan. The paint mist is separated from airflow by means of centrifugal force of the air produced in the eddy chamber, and the paint mist is collected as it impinges on a water film. The water containing the collected paint mist is returned from a submerged duct to a water tank and reused. The moist air discharged from the eddy chamber is discharged through an exhaust port after it is dehydrated by an eliminator.
On the other hand, a paint booth of the water booth type is disclosed in Japanese Patent No. 3704084 (Patent Document 2). In the paint booth of this type, a water curtain is formed by pouring water drawn up by a pump in the form of a film along a water flow plate. The paint mist is washed away when it contacts the water curtain. Further, shower water is sprayed from shower nozzles arranged on the back side of the water flow plate. By this shower water, the paint mist having failed to be collected by the water curtain is dropped into water.
In either of the paint booths disclosed in Patent Document 1 and Patent Document 2, collected paint mist drops together with water into the water tank and condenses. Therefore, paint sludge (paint residue) is produced in the water tank. This paint sludge collects in the water tank, floating on the water surface or settling in the water tank. Since the conventional paint booths do not comprise a mechanism for purifying water in the water tank, an operator or operators periodically manually remove the paint sludge. However, the periodic cleaning cannot purify contaminated water unless the water is changed. Accordingly, the paint sludge gradually collects in the water tank and solidifies at the bottom of the water tank or near the water surface. Thus, the paint sludge cannot be easily removed and causes contamination of the paint booth.
In the conventional Venturi booth type (Patent Document 1), moreover, a strong negative pressure must be produced to draw up water into the eddy chamber. A large-capacity exhaust fan is needed to attain this, resulting in problems of loud noise, high energy consumption, etc. In the conventional water booth type (Patent Document 2), in contrast, the paint mist contacts only one surface of the water curtain. Therefore, the surface area of the water curtain that can collect the paint mist is small. Thus, the conventional water booth type has a small capacity to collect the paint mist. To increase the collection capacity, a wider water curtain is required, so that the paint booth is enlarged, and a problem of necessity of a large-capacity pump or the like occurs.